Depression risk among breast cancer survivors: a nationwide cohort study in South Korea.

Background: Depression among breast cancer survivors is a significant concern affecting their long-term survivorship and quality of life. This study investigates the incidence of depression among breast cancer survivors and identifies associated risk factors.

Methods: This retrospective cohort study used data from the Korean National Health Insurance Service database and included 59,340 breast cancer patients without a history of depression who underwent surgery between January 1, 2010, and December 31, 2016. They were individually matched 1:2 by age with a general population without cancer (n = 99,834). The mean follow-up period was 6.4 ± 2.6 years. Sub-distribution hazard ratios (sHRs) and 95% confidence intervals (CIs) were calculated considering death as a competing risk and adjusting for sociodemographic factors and comorbidities.

Results: Breast cancer survivors with a mean (standard deviation) age of 51.5 (9.2) years had a 39% increased risk of depression compared to non-cancer controls (sHR 1.39, 95% CI 1.36-1.42). During the first year post-diagnosis, breast cancer survivors across all ages exhibited a significantly elevated risk of depression, with a sHR of 3.23 (95% CI 3.08-3.37). Notably, younger survivors had a sHR of 4.51 (95% CI 4.19-4.85), and older survivors had a sHR of 2.56 (95% CI 2.42-2.71). One year post-surgery, younger survivors (age ≤ 50 years) showed a 1.16-fold increase in depression risk (sHR 1.16, 95% CI 1.11-1.20), while older survivors (age > 50 years) showed no significant change in risk, which decreased over time. Use of anthracycline, taxane, or endocrine therapy was associated with an increased depression risk (sHR 1.17, 95% CI 1.13-1.22; sHR 1.12, 95% CI 1.07-1.16; and sHR 1.27, 95% CI 1.14-1.41, respectively), with endocrine therapy showing a 41% increased depression risk in older survivors (sHR 1.41, 95% CI 1.23-1.61).

Conclusion: This study demonstrates a significant association between breast cancer and depression, with a particularly heightened risk in younger survivors within the first year post-diagnosis. Special attention is needed to meticulously screen for depressive symptoms during the early follow-up years for breast cancer survivors who are premenopausal or have undergone chemotherapy and endocrine therapy.